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Shower Enclosure Calculator — Glass, Tray & Seal Sizing
Calculate shower enclosure panel sizes, tray dimensions, glass area, seal lengths and waste position based on your opening dimensions.
Width of the shower recess/opening
Depth from wall to front edge
Total enclosure kit price
Shower tray price
Per 2m seal strip
Standard: 1850mm or 1950mm
Per-side reduction off the opening (typically 10-30mm; check your profile)
Informational only — buy seals to match your glass thickness
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How We Calculate This
This calculator determines the correct shower enclosure panel sizes, tray dimensions and accessory quantities based on your opening measurements and chosen configuration.
The formula
Panel size = Opening width − Profile adjustment. The wall profiles let the enclosure sit slightly inside the opening; the adjustment is a manufacturer convention of roughly 10–30mm per side (15mm default here, editable under Advanced Options), not a fixed standard.
Glass area = Panel width × Panel height (per panel)
For a 900mm × 900mm rectangular enclosure at 1850mm height with a 15mm adjustment: front panel = 0.885 × 1.85 = 1.637 m², side panel = 0.885 × 1.85 = 1.637 m², total glass = 3.27 m².
The tray is sized to the largest standard size that fits within your opening (rounded down), because a tray that is wider than the recess cannot drop between the walls. For a 900mm opening that is a 900mm tray; for a 910mm opening it is still a 900mm tray.
Standard tray sizes (UK)
- Quadrant: 800×800, 900×900, 1000×1000mm
- Square: 700×700 to 1000×1000mm
- Rectangular: 900×760 to 1700×800mm
- Walk-in: 1200×800 to 1800×900mm
Frequently Asked Questions
Measure the opening where the enclosure will sit. Standard UK shower enclosure sizes are 700, 760, 800, 900, 1000, 1100, 1200mm wide. The enclosure is typically 10-30mm smaller than the opening to allow for adjustment on the wall profiles. A minimum of 760mm × 760mm is recommended for comfort, with 900mm × 900mm being the most popular size.
For a standard shower door or enclosure, 8mm toughened safety glass is the UK industry standard and offers a good balance of weight, rigidity and cost. 6mm is suitable for budget enclosures and bi-fold doors. 10mm glass is used for premium walk-in panels where the thicker glass provides better stability without a frame. All shower glass must be toughened safety glass to BS EN 12150.
Stone resin trays are the most popular choice in the UK, offering a solid feel, good durability and reasonable cost (£80-200). Acrylic trays are lighter and cheaper (£40-100) but can flex. Slate-effect trays offer a premium look (£150-350). For a truly flush finish, a tiled wet room former with linear drain is the ultimate option but requires proper tanking.
Centre waste is the most common and works with most enclosure types. Offset waste positions the drain towards one end, which is useful when plumbing access is limited. End waste works well with walk-in showers where you want the drain away from the entry point. Always check that the waste position aligns with your floor joists and soil pipe route.
There is no British Standard for seal quantity — it depends on the kit, so treat any figure as an estimate. A typical enclosed shower needs roughly 4-6 seal strips: two vertical wall seals where the glass meets the wall profile, one or two bottom seals where glass meets the tray, and a door seal. Walk-in panels need fewer — typically a wall seal and a floor seal. This calculator estimates the run by summing the vertical edges (full height) and the bottom edges (along the tray) and dividing by the 2m strip length. Standard seal strips are 2m long and available in 4mm, 6mm and 8mm widths to match the glass thickness.
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Last updated: March 2026
Verified against UK standards · estimates only, confirm with your supplier.